Arrangement for controlling the gas discharge in electric discharge vessels



Oct. 2, 1934. w DALLENBACH 1,975,714

ARRANGEMENT FOR CONTROLLING THE GAS DISCHARGE IN ELECTRIC DISCHARGE VESSELS Filed March 25, 1935- 2 Sheets-Sheet 1 Fig.1

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Oct. 2, 1934. w. DALLENBACH ARRANGEMENT FOR CONTROLLING THE GAS DISCHARGE IN ELECTRIC DISCHARGE VESSELS 2 Sheets-Sheet 2 Filed March 25 1955 /n ven fofi: [14? 72 6223871812 Ea c/z Patented Oct. 2, 1934 ARRANGEMENT FOR CONTEOLLING THE GAS DISCHARGE IN ELECTRIC DISCHARGE vassans Walter Dillenbach, Berlin-Charlottenburg,

' Germany Application March 25, 1933, Serial No. 662,776 In Germany March 26, 1932 21 Claims.

My invention relates to an improvement in arrangements for controllinga gas discharge in electric discharge vessels which are filled with rarefied gas or vapour, e. g. regulable rectlfiers,

inverters and converters filled with rarefied merc'ury vapour and having mercury or incandescent cathodes. In particular my invention relates to an arrangement for such discharge vessels in which a control electrode, a so-called blocking electrode, is arranged between anode and cathode and is maintained at a voltage which is negative with respect to the cathode.

As is known such a control electrode maintains in its vicinity an electrostatic field and the anode which is positively charged at the desired time of ignition is not able or is able, only on attaining a sufllciently high positive voltage, to overcome this electrostatic field and to attract from the vicinity of the cathode or from the atmosphere of ions on the remote side of the control electrode the carriers of electric charge, particularly electrons. The spacial extent towards the cathode or into ionized gas atmosphere of the electrostatic field maintained by the negative voltage of the control electrode is dependent substantially on two physical magnitudes. These are, in the first place, the negative voltage which is applied to the control electrode relatively to the cathode or to the ionized gas atmosphere, and secondly, the inflow of positive ions to the control electrode from the cathode or ionized gas atmosphere. The dependence of the spacial extent of the blocking field on these two independent variables determines the so-called space charge equation which in the case of a plane arrangement of the electrodes, i. e. in the unidimensional case, assumes the simple form:

Current density equals a constant multiplied by the voltage raised to the power of 3/ 2 divided by the square of the spacial extent of the blocking field.

Thus the spacial extent of the blocking field is the greater the greater the negative voltage between the blocking electrode and the cathode or the ionized gas atmosphere, and the smaller the current of positive ions which flows to the blocking electrode from the cathode or from the ionized gas atmosphere.

Now it is one feature of my invention to overcome the blocking action of such a blocking electrode by supplying positive ions to an increased extent to the blocking electrode which remains at substantially unaltered potential. The blocking electrode can be wholly or only in part located in the stream of positive ions. In this way the particularly the electrons.

My invention is not limited to a particular means for producing the positive ions and any suitable means can be used for this purpose.

Certain particularly preferred means constitute further features of my invention. For example, a coil or twoelectrodes excited with high frequency can be disposed in the vicinity of the blocking electrode inside or outside the discharge 7 vessel. By means of the high frequency field thus produced at a predetermined instant of time, an intensive ionization is occasioned in the vicinity of the blocking electrode and gives rise to a considerable increase in .the supply of positive ions to the negatively charged blocking electrode.

A further feature of my invention is to provide an auxiliary electrode 7 which preferably passes through the apertures in the blocking electrode and to which a positive voltage is applied at a predetermined instant of time. In consequence of this positive charge, the auxiliary anode attracts electrons which gives rise to positive ions in the vicinity of the blocking electrode.

Further features of my invention are set out in the following description and in the drawings which constitute a part of my application:

In the drawings, Fig. 1 diagrammatically shows one embodiment of the invention.

Fig. 1a. shows the same embodiment in a difierent operative condition which is indicated schematically.

Fig. 2 diagrammatically shows a further embodiment in which the suspension of the blocking action is controlled by means of a rotary contact device.

Fig. 2a is a plan view of this contact device on a larger scale,

Fig. 3 shows a particular constructional form of the blocking electrode,

Fig. 4 a particular embodiment of the electrode for causing positive ions-to flow over the blocking electrode,

Figs. 5 and 6 diagrammatically show two further embodiments in which the suspension of the blocking action is automatically controlled,

Fig. '7 is an embodiment for a gas discharge vessel with a number of anodes.

1 is a gas discharge vessel of any suitable construction, 2 the cathode, e. g. a mercury cathode,

and 3 is the anode which is connected by way of a transformer 17, for example, to the alternating current mains 18. A blocking electrode 4 is disposed in front of the anode. This blocking electrode may, for example, consist of a grid of parallel bars which are secured in a frame 5. By means of the sealed-in leads 6 and 6 this frame is secured in the vessel 1. A voltage negative relatively to the cathode 2 is imparted to the blocking electrode 4 by means of the battery 7 and the series resistance 8 so that with the positive voltages on the, anode which occur in operation, the anode is not capable of operating through the blocking electrode. On the other hand, the blocking field extends up to the boundary which is indicated at 9 at which the greatest part of the electrons which tend to penetrate from the space beneath 9 towards the blocking electrode are electrically reflected. The ionized gas atmosphere located beneath the boundary 9 is maintained by means of the excite-r arc passing to the exciter electrode 10 and fed by the battery 12 by way of the series resistance 11.

If in Fig. 1, x indicates the distance from the blocking electrode 4 to the boundary 9 of the ionized gas atmosphere, V the voltage of the blocking electrode relatively to the ionized gas atmosphere and J the density of the positive ion stream from the boundary of the ionized gas atmosphere 9 towards the blocking electrode 4, then the space charge formula,

V"' x const.

approximately holds.

In the vicinity of the blocking electrode 4, the vessel 1 is surrounded by a high frequency coil 13 which is enclosed by an insulating tube 14.

The coil 13 may be disposed outside the vessel 1 as shown in the drawings or may be disposed within the vessel. Instead of a coil, two semicylindrical or similarly shaped electrodes 32 and 33 such as are shown in Fig. 4. can be used inside or outside the vessel.

Energy is supplied to this coil 13 or to the electrodes 32, 33 from a high frequency generator 15. If now the switch 16 in the exciter circuit of the high frequency coil or electrodes is closed, then an intensive ionization which involves a considerable increase in the supply of positive ions to the negatively blocking electrode, is occasioned in the vicinity of the blocking electrode. Consequently, the spacial extent a: of the blocking field drops very rapidly to very small values so that the blocking field is confined to the surface layers 30 indicated in Fig. 2 which concentrically surround the individual bars of the blocking electrode. Between these bars there remain free spaces which are not filled by the blocking field and through which the electrons of the ionized gas atmosphere can now penetrate from the vicinity of the cathode to the positively charged anode.

' It is desirable to make the frequency of the gen-- ignition and discharge voltage of the high frequency gas discharge within the tube.

The direct current voltage produced is taken off in known manner at 19.

In many cases it is sufficient for the blocking electrode 4 to be connected continuously inside or outside the discharge vessel with the cathode 2 either directly or what is better by way of a resistance.

As even when it is not connected with a source of current, the electrode still acquires a negative charge under the influence of the gas discharge occurring within the tube, it is not necessary if the main anode 3 operates to a sufiiciently small extent through the blocking anode 4 to apply a separate potential to the latter from an independent source but it is sufficient if the blocking electrode 4 is at the potential which it automatically assumes due to contact with the gas discharge. Such a small action is attained if, for example as shown in Fig. 3, plates 31 disposed on edge are used instead of rods, these plates being arranged parallel or in grid-form. If these plates are sufficiently high the anode 3 cannot operate through the blocking electrode even with small negative potential thereof.

The embodiment according to Fig. 2 is differentiated from that according to'Fig. 1 only in that instead of the switch 16 a rotating contact device is provided. This consists of a disc of insulating material in which is inserted the contact element 21. The disc is driven by means of a belt or the like from a synchronous motor 24 which is connected to the supply mains 18. A lever 25 which can be pivoted by means of the knob 26 is carried on the same shaft 22 as the disc 20 or on a separate shaft. This lever carries two contact fingers 27 and 28 which are included in the exciter circuit of the coil 13 and slide over the disc 20. As soon as the contact element 21 of the constantly rotating disk 20 connects the two contact fingers the coil 13 is energized so that the'blocking field of the block ing electrode is reduced and in consequence the discharge starts. By moving the arm 25 the instant at which the contact fingers 2'7 and 28 are joined the time of excitation of the coil also can thus be varied relatively to the instant at which the alternating voltage applied to the anode 3 becomes positive. In this way the excitation of the coil 13 which gives rise to the ignition can be used for the regulatable control of the gas discharge in synchronism with an alternating voltage applied to the main anode 3.

Positive ions can also be caused to flow over the blocking electrode 4 by applying to an auxiliary anode a voltage which is positive with respect to the cathode.

Such an arrangement is shown in Fig. 5. The auxiliary anode 36 with the anode head 35 receives its voltage from a phase displacer which is connected with the three-phase mains 34. The phase displacer consists in known manner of a Grarnme ring 38, an armature '39 and a field winding 40 which is connected with the auxiliary anode 35--36 and the cathode 2. By rotating the armature 39, the instant at which the alternating current applied to the auxiliary anode becomes positive can be varied in known manner with reference to the instant at which the main anode 3 is positively charged.

If the adjustability of this instant of time is dispensed with, the auxiliary anode 35, 36, may be connected to a battery, the circuit of which is closed by means of a manual switch.

The embodiment according to Fig. 6, shows an auxiliary anode 42 which has a portion 41 extended spacially in the direction of the discharge. A suitable resistance material, e. g. thin wire can be used as material for the auxiliary anode. In consequence of the voltage drop the discharge begins at the lower end of the auxiliary anode 41 and then rises upwardly. The exciter voltage of the auxiliary anode 41, 42 is derived by way of a series resistance 44 from the transformer 45 which is connected to the mains 18. In order to be able to alter the instant of time at which the positive charge in consequence of which the gas discharge commences is applied to the auxiliary anode, a source of direct current 46 is connected in series with the transformer 45 and the cathode 2. By means of a movable contact 47 different direct current voltages can be tapped off from this source of direct current. If the movable contact 4'? is positioned at the centre of the battery 46, then the pure alternating voltage determines the instant of time at which the auxiliary anode becomes positive. As soon as the contact 47 is displaced, the auxiliary anode becomes positive earlier or later in accordance with whether a positive or a negative direct voltage is superimposed on the alternating voltage. stead of such a regulatable exciter arrangement, it would also be possible in this case to use a simple battery with a manual switch.

The embodiment according to Fig. '1 shows a gas discharge vessel 48, e. g. a rectifier vessel in which a number of anodes 50 are arranged opposite a cathode 49. Associated with each anode is a separate blocking electrode 4, the blocking electrodes being interconnected so that they have all the same common negative potential. This is applied to them from the battery 52 by way of the resistance 51. For the rest this arrangement corresponds to that according to Fig. 1 so that further explanation is not necessary.

Attention is however directed to the fact that instead of the switch 16, one of the regulatable exciter arrangements described above can be used. Further, instead of the high frequency coil 13, a high frequency electrode or an auxiliary electrode can be employed as in the remaining examples.

The invention is not limited to the embodiments set out above but for carrying out the inventive idea any process can be used which for suspending the blocking action enables positive ions to be caused to flow in part at least over the blocking electrode with constant negative potential of the electrode.

What I claim is:

1. An electric gas discharge vessel comprising an anode and a cathode, means for applying to the anode a voltage positive at the desired instant of ignition and which will generate a field which attracts negative charge carriers, a block ing electrode between the anode and cathode, means for continuously maintaining on said blocking electrode a voltage negative with respect to the cathode, said voltage being adapted to generate an electrostatic blocking field which normally prevents the passage through the blocking electrode of the negative charge carriers attracted by the anode field, means for producing in the gas discharge vessel at an optionally changeable time positive ions which flow over the blocking electrode at least partially to reduce the spacial extent of the blocking field to a magnitude permitting the passage of negative charge carriers.

2. An electric gas dischar vessel comprising an anode and a cathode, mea s for applying to the anode a positive voltage at the desired instant of ignition and which will generate a field which attracts negative charge carriers, a block-- ing electrode between anode and cathode, a permanent connection between said blocking electrode and the cathode whereby the blocking electrode produces an electrostatic blocking field which normally preventsthe passage through the blocking electrode of the negative charge carriers attracted by the anode field, means for producing in the gas discharge vessel at an optionally changeable time positive ions which flow partially at least over the blocking electrode to reduce the spacial extent of the blocking field to a magnitude permitting the passage of negative charge carriers.

3. In an electric gas discharge vessel according to claim 2, a resistance included in the connection between blocking electrode and cathode.

4. In an electric gas discharge vessel an anode and a cathode, means for applying to the anode a voltage positive at the desired instant of ignition which will generate a field which attracts negative charge carriers, a blocking electrode between the anode and cathode, said electrode consisting of a plurality of plates disposed on edge and arranged in parallel, the electrostatic field produced by reason of this blocking electrode by contact with the gas discharge in the interior of the gas discharge vessel being adapted normally to prevent passage through the blocking electrode of the negative charge carriers attracted by the anode field, means for generating in the gas discharge vessel at an optionally changeable time positive ions which fiow at least in part over the blocking electrode to reduce the spacial extent of the blocking field to a magnitude permitting the passage of negative charge carriers.

5. An electric gas discharge vessel, an anode and a cathode in said vessel, means for applying to the anode a voltage positive at the desired instant of ignition which will generate a field which attracts negative charge carriers, a blocking electrode between the anode and the cathode, means for continuously maintaining the blocking electrode at a voltage negative with respect to the cathode, said negative voltage being adapted to produce an electrostatic blocking field whichnormally prevents passage through the blocking electrode of the negative charge carriers attracted by the anode field in the vicinity of the blocking electrode, means for producing high frequency fields which occasion a fiow of positive ions over the blocking electrode, switch means for causing the excitation of the high frequency fields at an optionally changeable instant to reduce the spacial extent of the blocking field to a magnitude permitting the passage of negative charge carriers.

6. In an electric gas discharge vessel according to claim 5, said means for producinghigh frequency being adapted to produce high frequency of the order of magnitude of 10 to 10 periods per second.

7. An electric gas discharge vessel, an anode and a cathode therein, means for applying to the anode a voltagepositive at the desired instant of ignition which will produce a field which attracts negative charge carriers, a blocking elecsufficient for the ignition of a high frequency discharge, a source of high frequency for exciting said winding, and a switch device for closing the exciter circuit of the highfrequency winding at an optionally changeable instant.

8. An electric gas dischargevessel, an anode and a cathode therein, means for applying to the anode a voltage positive at the desired instant of ignition which will produce a field which attracts negative charge carriers, a blocking electrode between the anode and the cathode, means for maintaining said blocking electrode constantly at a voltage negative with respect to the oathode, said negative voltage being adapted to produce an electrostatic blocking field wh ch normally prevents the passage through the blocking electrode of the negative charge carriers attracted by the anode field, two electrodes adapted to produce high frequency fields in the vicinity of the blocking electrode of an energy suflicient for the ignition of a high frequency discharge, a source of high frequency connected with the two electrodes, and a switch device in the connection between the two electrodes and the source of high frequency.

9. An electric gas discharge vessel, an anode and a cathode therein, means for applying to the anode a voltage positive at the desired instant of ignition which will produce a field attracting negative charge carriers, a blocking electrode between the anode and the cathode, means for maintaining said blocking electrode continuously at a voltage negative with respectto the cathode, said negative voltage being adapted to produce an electrostatic blocking field which normally prevents the passage through the blocking electrode of the negative charge carrlers attracted by the anode field, an auxiliary anode in the gas discharge vessel, a source of current connected with the auxiliary anode for producing a voltage which at least is temporarily positive, and a switch device in the connection between auxiliary anode and source of current for applying the positive voltage to the auxiliary anode at an optionally changeable instant, whereby in consequence of its positive charge the auxiliary anode attracts electrons with resulting formation of positive ions in the vicinity of the blocking electrode.

10. In an electric gas discharge vessel according to claim 9, said auxiliary anode operating through the blocking electrode towards the oathode to a greater extent than the main anode.

11. In an electric gas discharge vessel according to claim 9, said auxiliary anode extending spacially in the direction of the path of the discharge.

12. In an electric gas discharge vessel according to claim 9, said auxiliary anode passing through the blocking electrode.

13. In an electric gas discharge vessel according to claim 9, said auxiliary anode being of resistance material in the form of thin bars.

14. An electric gas discharge vessel, an anode and a cathode therein, means for applying to the anode a voltage positive at the desired instant of ignition which will produce a field which attracts negative charge carriers, a blockcharge carriers attracted by the anode field, a high frequency winding arranged in the vicinity of the blocking electrode for producing high frequency fields in the vicinity of the blocking electrode of an energy sufficient for ;,the ignition of a high frequency discharge, a source of high frequency for exciting said winding, a rotary contact device included in the exciter circuit of the high frequency winding for automatically closing the exciter circuit at optionally changeable intervals of time, and means for displacing the instant of closure with respect to the instant at which the main anode is positive.

15. An electric gas discharge vessel, an anode and a cathode therein, means for applying to the anode a voltage positive at the desired instant of ignition which will produce a field which attracts negative charge carriers, a blocking electrode between the anode and the cathode, means for maintaining said blocking electrode constantly at a voltage negative with respect to the cathode, said negative voltage being adapted to produce an electrostatic blocking field which normally prevents the passage through the blocking electrode of the negative charge carriers attracted by the anode field, two electrodes for producing high frequency fields in the vicinity of the blocking electrode, a source of high fre quency connected with the two electrodes, a rotating contact device in the connection between the two electrodes and the source of high frequency for automatically closing this connection at optionally changeable intervals of time, and means for adjusting the instant of closure with respect to the instant at which the main anode is positive.

16. An electric gas discharge vessel, an anode and a cathode therein, means for applying to the anode a voltage positive at the desired instant of ignition which will produce a field which attracts negative charge carriers, a blocking electrode between the anode and the cathode, means for maintaining said blocking electrode constantly at a voltage negative with respect to the cathode, said negative voltage being adapted 'to produce an electrostatic blocking field which normally prevents the passage through the blocking electrode of the negative charge carriers attracted by the anode field, an auxiliary anode in the gas discharge vessel, a source of alternating current connected to said auxiliary anode, means for displacing the phase of the alternating current fed to the auxiliary anode whereby the instant at which the auxiliary anode becomes positive is altered.

17. In anelectric gas discharge vessel according to claim 16, a phase displacer included in the connection between auxiliary anode and source of alternating voltage, the armature winding of said phase displacer being connected in series with the auxiliary anode and the cathode.

18. An electric gas discharge vessel, an anode and a cathode therein, means for applying to the anode a voltage positive at the desired instant of ignition which will produce a field which attracts negative charge carriers, a blocking electrode between the anode and the cathode, means for maintaining said blocking electrode constantly at a voltage negative with respect to the cathode, said negative voltage being adapted to produce an electrostatic blocking field which normally prevents the passage through the blocking electrode of negative charge carriers attracted by the anode field, an auxiliary anode in the gas discharge vessel, a source of alternating voltage tit) wit

connected to said auxiliary anode, a source of direct current voltage superimposed on the alternating voltage applied to the auxiliary anode,

and means for regulating the magnitude of the 6 direct current voltage superimposed on the alternating current voltage.

19. An electric gas discharge vessel, an anode and a cathode therein, means for applying to the anode a potential positive at the desired instant of ignition which will produce a field which attracts negative charge carriers, a blocking electrode between the anode and the cathode, means for maintaining said blocking electrode constantly at a negative voltage with respect to the cathode, said negative voltage being adapted to produce an electrostatic blocking field which normally prevents the passage through the blocking electrode of the negative charge carriers attracted by the anode field, a source of alternating voltage, a transformer connected to said source of alternating voltage in the gas discharge vessel, an auxiliary anode connected to the secondary side or said transformer, a source of direct current voltage connected in series with said auxiliary anode, the secondary winding of the transformer and the cathode, and an adjustable contact adapted to vary the magnitude the applied direct current voltage.

20. An electric gas discharge vessel, a number or anodes and a cathode therein, means for applying to the anode a voltage positive at the desired instant of ignition for producing fields which attract negative charge carriers, a blocking electrode between each anode and said cathode, said blocking electrodes being maintained constantly at a voltage negative with respect to the cathode, said negative voltage being adapted to produce electrostatic blocking fields which normally prevent the passage through the blocking electrodes of negative charge carriers attracted by the anode fields, a connection between the various anodes, means associated with each blocking electrode for producing in the gas discharge vessel at an optionally changeable instant positive ions which fiow over the blocking electrodes at least in part, and reduce the spacial extent of the blocking fields to a magnitude permitting the passage of negative charge carriers.

21. A method of reducing the electrostatic field set up by the negative charge on a blocking electrode positioned between the anode and cathode of an electric gas discharge vessel; which consists in causing positive ions to fiow at least in part over the blocking electrode, whereby the electrostatic field is reduced to such an extent as to permit the passage or negative charge carriers.

WALTER DALLENBACH. 

